Subject: Re: [mobile-ip] Mobile Prefix Advertisements, take 2

From: [email-masked]
Date: Sat, 28 Sep 2002 11:41:10 +0530

>
> It would be nice if we could have some input on these formulae. Here are
some
> proposed changes to synchronize everything and some questions:
>
> - HomeRtrAdvInterval should be renamed, perhaps to MaxMobPfxAdvInterval
>
> - formula for MAX_SCHEDULE_DELAY should use MaxMobPfxAdvInterval instead
of
> MAX_PFX_ADV_DELAY
>
> - Is there some reason why we need a separate variable,
MAX_PFX_ADV_DELAY? It
> seems like it should always be equal to MaxMobPfxAdvInterval. Correct?
Maybe we
> can just get rid of it and the mobile node can use the same value defined
for
> the latter.
>
> - RAND_ADV_DELAY uses MinRtrAdvInt. But this is for router advertisements
at
> the home agent. Perhaps we also need to define a MinMobPfxAdvInterval to
set
> the min bound for MPAs.
>
> - What should the best values for {Max,Min}MobPfxAdvInterval be?
>
>
>
> Hope that is a better explanation!
>
> -TJ

Thanks TJ, it is quite clear now.

Well, I agree with your suggestions. There should be something like
{Max, Min}MobPfxAdvInterval for Mobile Prefix Advertisements.

For MaxMobPfxAdvInterval we can keep the same value as for
HomeRtrAdvInterval i.e. 3,600 secs as specified in draft-18 and for
MinMobPfxAdvInetrval may be somthing less than 60 secs as we have to
consider the RAND_ADV_DELAY also.

I have few more doubts regarding when to send Mobile Prefix Advertisements
from HA.
It is clear that HA will send unsolicited periodic Mobile Prefix
Advertisements with all Prefix Information options at every
HomeRtrAdvInterval (3,600 secs) to MN after registration.

1) For these advertisements do we need to wait for any acknowledgements
from MN ?

Also HA will send unsolicited MPA to MN if there is any change in parameter
of the  prefix of the MN's registered Home Address.

2) In this case do we need to send all the prefix information options
advertised on the   link or only the changed prefix information option ?

Draft says - The home agent SHOULD periodically continue to retransmit an
   unsolicited Advertisement to the mobile node, either until it is
   acknowledged by the receipt from the mobile node of a Binding Update
   with a home address matching the new home prefix in the packet,
   or until the home agent receives a Mobile Prefix Solicitation
   form the mobile node.

3) In which case MN will send Mobile Prefix Solicitation as acknowledgement
to             unsolicited MPA? If any parameter related to prefix changes
then MN should send BU directly to HA and this can be used as
acknowledgement for MPA.

 - Sourajeet